Door stop



FIG. 1 is a perspective view of a door stop showing my new design, with a part of the door being shown by phantom lines for illustrative purposes only;

FIG. 2 is a rear elevation (at the right hand side) of FIG. 1;

FIG. 3 is a front elevation of FIG. 1; and

FIG. 4 is a top plan view. 

The ornamental design for a door stop, substantially as shown and described. 